In the bottling industry, containers, and in particular bottles made of a plastics material of the PET or PVC type are conventionally transported via a pneumatic path between an upstream machine for manufacturing said containers by blow-molding, and a downstream machine for filling said containers. More particularly, such transfer lines implement pneumatic conveyors in which the containers are suspended via projections on their necks and are pushed one behind the other under the action of air jets. In practice, the output rates of such pneumatic transfer lines lie in the range 10,000 containers per hour to 60,000 containers per hour.
Clearly, for reasons of hygiene, it is necessary in such bottling lines to ensure that the insides of the containers are not contaminated with bacteria prior to being filled. For this purpose, it is possible, for example, to inject a disinfectant into the containers while they are being transferred pneumatically, it then being necessary to maintain said disinfectant at a determined temperature for a predetermined optimum duration, e.g. at 50.degree. C. for ten minutes. In which case, it is necessary to make sure that each container containing the disinfectant is maintained at this temperature for an actual duration that remains in the range set by a maximum duration that should not be exceeded and by a minimum duration below which the action of the disinfectant is not effective enough.